Electrostatic sound reproducer



Jan. 20, 1931. c. KYLE 1,789,554

ELECTROSTATIC SOUND RBPHODUCER Filed July 11. 1928' I r &

lllll producers and reproducers,

i shape Patented Jan. 20, 1931 UNITEDTATES COLIN, KYLE, OF GENEVA, ILLINOIS,

BEPRODUCERS PATENTS CORPORATION, OF ST.

0] NEVADA.

PATENT Q oFFI-CE ELECTROSTATIC scum) 'nurnoruonn Applioation'flled m 11, ms. 9.... in. 891,888.

The present invention relates to sound such as those used in radio reception, and has reference more particularly to the type known as electro-static'sound producers and reproducers.

It is regarded as an improvement of that disclosed in the patent to Kyle, No. 1,644,387, granted October 4, 1927, and those disclosed in co-pending applications of Jesse B. Hawley, Ser.- Nos. 259,717, and 261,495, filed March 7, and 14:, 1928, respectively. 7

Among the objects of the invention is to provide a novel sound producer and reproducer of the electro-static type and having an. electrically conducting member, such as a metal plate having an undulated form or w1th apertures or holes distributed over the plate for location in the crests, slopes, and troughs of the undulations for release of compressions, and rarefactions of air at all points or loci thereof, and having a thin flexible dielectric associated therewith to flex toward the slopes and troughs of the undulations, the outer surface or that opposite from the surface adjacent the crests, hav-.

ing a flexible conducting coat or the like, such as gold, silver, aluminum foil, sprayed metal or conducting substance, and the like. The plate is preferably generally convex surface, and the dielectric is normally made to extend against the convex side of the plate and in contact therewith.

on the crest lines of the undulations. The dielectric may be of any suitable material, such as sheet rubber, rubberized fabric, piano cloth, such as rubberized silk, and other like and similar dielectric materials.

When the dielectric portions between the crest lines, flexby reason of the electro-static attraction or repulsion of the proximate portions of the slopes of the undulations, there is a compression or rarefaction of air in the dihedral angle between such slope and the flexed portions of the dielectric. In the case of attraction, the greatest attraction is at the parts most proximate to each other, such as at or adjacent the line of contact. If the receding parts of the crests and the slopes be not provided with relief openings, it will become apparent that the compression curved to offer a' stresses travel laterally and toward the opening in the troughs, when such are provided in such troughs. The reaction of these" stresses on the flexing parts of the dielectric appears to be greater against the dielectric parts that are less attracted by the electrostatic charge on the plate by reason of the greater distance between these parts of the dielectric and the corresponding parts of the slopes and troughs. The invention, therefore, comprehends, as an important feature thereof, the provision of means for releasing the compressions at substantialy all points or loci, the holes being in the crests, curved portions of the crests, in the S10 es, the

curved portions of the troughs an in the As a result of this' construction, the sound proceeds from the vibrating dielectric without any sense of direction, the sound appearing to be emitted from every point radially in every direction.

Other objects, advantages, capabilities and features are comprehended by the invention as will later appear, and as are inherently possessed thereby.

Referring to the drawings:

Fig. 1 is a perspective view with parts broken away of an electro-static sound producer constructed in accordance with the invention;

Fig. 2 is a fragmentary sectional view through a part of the device; 1

' Fig. 3 is a fragmentary view in elevation of a part of the metal plate used in the device Fig. 4 is a fragmentary sectional view through a plate having elongated apertures;

and

Fig. 5 isa fragmentary view in elevation of the plate shown in Fig. 4. I

Referring now more in detail, to the drawings, the embodiment selected to illustrate the invention is shown in connection with a frame 1 having side pieces 2 and top and bot- .tom pieces 3. The forward edge portions of vex edges of the top and bottom pieces of the device.

The plate is also provided with a numberof apertures or holes 8, 9, 10, 11, and 12, such that the apertures 8 are located in the crest portions, while apertures 9 and 10 are in the slope portions of the undulations, and apertures 11 and 12 are in the trough portions, as clearly shown in Fig. 2 of the drawings. It will be noted that the plate is of general convex form, and against the outer surface of the same is stretched a suitable thin flexible dielectric 13 with the dielectric normally in contact with the crest portions of the undulations and with the ends of the dielectric suitably secured to the side pieces 2 of the frame.

On the outer or convex surface of the dielectrio is provided a flexible conducting coat of material, such as gold-leaf, silver-leaf, aluminum-leaf or foil, or sprayed metal and other conducting substance, and other like and similar thin, flexible conducting material.

The plate 4 and the conductin surface 14 are, in practice, connected to t e opposite sides of the output circuit of an audio amplifying device or the like, whereby the charges in the plate 4 and foil 14 may vary in accordance with the audio variations in the electric circuit. When the charge in the plate 4 is an attracting charge, the dielectric and flex-. ible conductor, is caused to move toward the plate with portions opposite the $10 s and troughs flexed, as shown in the dotted 'ne position thereof in Fig. 2. The depth of the trough is preferably at least as great as and preferably greater than the greatest amplitude of movement of the lowest audible tone to be reproduced. As the dielectric flexes, the portion 15 thereof near the curvatureof the crest, or the start of the slope of the undulations, will be attracted throu h the small narrow angle 16 with greater orce than at more remote loci. This attraction will progress along the slope as the dielectric is flexed toward the plate. It will thus be noted that with the apertures being located at the various points indicated, any compression of air tending to be effected in the dihedral angle between the flexed portion of the dielectric .One set of a and the s10 ing and curved ortions of the plate, will immediately re eased, and the dielectric be free to act under the attractin forces of the charges between the plate and thedielectric or the conducting coat thereon. Likewise, when the charges are of the repelling type, the flexing of the diaphragm is in the op osite directionor away from the surface 0 the plate, and rarefaction is released through the same apertures or openings, to allow'free movement of the dielectric and flexible coating thereon.

In Figs. 4 and 5 is shown a plate similar to that shown in Figs. 2 and 3, with the exception that the apertures therein are elongated. rtures 17 is located in the crests and extend 1nto the sloping parts thereof or in the slopes of the undulations. Another set of apertures 18 is located in the slopes with portions extending toward the crest or into the curved portions thereof and into the curved portions of the troughs. A third set of apertures 19 is located in the troughs with the ends extending into the slopes. The action of these apertures is similar to that described above in connection with the form of plates shown in Figs. 1, 2 and 3.

While I have herein described and upon the drawings shown a few embodiments of the invention, it is to be understood that the latter is not limited thereto, but may comprehend other constructions, arrangements of parts, details, and features, without departin from the spirit thereof.

aving thus disclosed the invention, I claim:

1. An electro-static sound reproducer comprising an electrically conducting member having a continuously undulating surface, said member having apertures in the slopes and troughs of the undulations, a flexible dielectric extending normall over the crests of the undulations, and a coating on the opposite surface of the dielectric.

2. An electro-static sound reproducer comprising an electrically conducting member having a continuously undulating surface, said member having apertures distributed over the member, a flexible dielectric extending normally over the crests of the undulathe opposite surface of the dielectric, said apertures being so located as to relieve pressure and rarefaction substantially normally to the flexed portions of the dielectric.

3. An electro-static sound reproducer, comprising a frame having a convex side, a continuously undulated metal plate secured to said side and being generally 'convex, a flexible dielectric extending over the convex side of said plate and over the crests of the undulations thereof, said plate having apertures distributed over parts thereof, and a flexible exible conducting tions, and a flexible conducting coating on conducting coating on the outside surface of said dielectric.

4. An electro-static sound reproducer, comprising a frame having a convex side, a continuously undulated metal plate secured to said side and being generally convex, the undulations of said plate being parallel to the axis of curvature of said late, a flexible dielectric extending over the convex side of said plate and over the crests of the undulations thereof, said plate having apertures distributed over parts thereof, and a flexible conducting coating on the outside surface of said dielectric.

5. An electro-static sound reproducer comprising an electrically conducting member rovided with a continuously undulated surace, said member having apertures distributed over the slopes and troughs of the undulationsthereof, a thin dielectric extending over the crests of the undulations, the portions of the dielectric o posite the slopes and troughs being adapts to flex toward said slo' es and troughs, said apertures being capa le of relieving compression and rarefaction of. air substantiall at a normal to the flexed parts of the die ectric, and a flexible conducting coat on the outer surface of the dielectric.

6. An electro-static sound reproducer comprising an electrically conducting member aving a continuously undulating surface, said member having apertures in the troughs of the undulations, a flexible dielectric extending normally over the crests of the undulations, and a flexible conducting coating on the opposite surface of the dielectric.

In witness whereof, I hereunto subscribe my name to this specification.

. COLIN KYLE. 

